A clinical trial investigating the potential role of interleukin 2 in the treatment of patients with cancer has been designed. This trial will test the toxicity of both natural and recombinant interleukin 2 preparations when given subcutaneously, intraperitoneally, intravenously (slow or by i.v. push), or intramuscularly in escalating doses. Concomitantly, we will study the pharmacokinetics and immunomodulatory dose properties of both recombinant and natural interleukin 2 when given by these five routes in escalating doses. Finally, in an attempt to evaluate the possible antitumor effects of interleukin 2 in cancer patients, we will administer the agent for three weeks on a daily basis at either the optimal immunomodulatory dose (as determined by our in vitro immunomonitoring assays), at one tenth of the optimal immunomodulatory dose, or at 10 times the optimal immunomodulatory dose, provided that this dose is below the maximum tolerated dose (defined from previous toxicity testing).